U.S. patent number 4,976,674 [Application Number 07/489,455] was granted by the patent office on 1990-12-11 for bag and method of making the same.
This patent grant is currently assigned to American Packaging Corporation. Invention is credited to Jeffrey D. Muhs, Gilbert N. Yannuzzi, Jr..
United States Patent |
4,976,674 |
Yannuzzi, Jr. , et
al. |
December 11, 1990 |
Bag and method of making the same
Abstract
The bottom of a gusseted, square-bottom bag is sealed by
applying a fin seal, a cross seal which intersects the fin seal,
and a third seal at the intersection of the fin seal and the cross
seal.
Inventors: |
Yannuzzi, Jr.; Gilbert N.
(Richboro, PA), Muhs; Jeffrey D. (Sun Prairie, WI) |
Assignee: |
American Packaging Corporation
(Philadelphia, PA)
|
Family
ID: |
23943935 |
Appl.
No.: |
07/489,455 |
Filed: |
March 6, 1990 |
Current U.S.
Class: |
493/195; 493/208;
493/243; 493/253; 493/217 |
Current CPC
Class: |
B31B
70/644 (20170801); B31B 70/00 (20170801); B31B
70/64 (20170801); B31B 2150/0014 (20170801); B31B
2160/10 (20170801); B31B 2160/20 (20170801); B31B
2150/00 (20170801) |
Current International
Class: |
B31B
19/00 (20060101); B31B 19/64 (20060101); B31B
29/00 (20060101); B31B 001/64 (); B31B
049/04 () |
Field of
Search: |
;493/193,199,200,201,218,228,231,241,242,341,355,217,220,243,253,264,265,208,197
;383/115,126 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schmidt; Frederick R.
Assistant Examiner: Marlott; John A.
Attorney, Agent or Firm: Follmer; Frank A.
Claims
What is claimed is:
1. A method of making a bag of the gusseted squarebottom type
comprising the steps of:
forming a tube having an outer sheet and an inner liner of an
imperivous material, with said liner being adhered to the outer
sheet at the mating surfaces thereof,
forming a pair of spaced-apart parallel slits in one of said tube
walls extending inwardly from an edge to define a tab portion,
forming the bottom end of the bag into a diamond fold with the tab
portion at one end thereof and a triangular portion at the other
end thereof,
applying pressure seals to the diamond fold to completely seal the
bottom end of the bag,
said sealing step including a first sealing step wherein the
diamond fold is heat and pressure sealed along the apex thereof to
form a fin seal, a second sealing step wherein the diamond fold is
heat and pressure sealed along an area adjacent said tab portion
and extending transversely to said fin seal to form a cross seal
intersecting with said fin seal, and a third sealing step wherein a
pressure seal is applied across a substantial area at the
intersection of said fin seal and said cross seal to provide a
strong seal at this location to prevent leakage thereat,
and completing the bag bottom by folding over the triangular
portion and said tab portion and adhere the same together to
complete the formation of the bottom of the bag.
2. A method according to claim 1 wherein said third sealing step is
applied over a generally rectangular area generally centered at
said intersection of said fin seal and said cross seal.
3. A method according to claim 2 wherein said third sealing step is
performed immediately after said second sealing step.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates generally to bags of the gusseted,
square-bottomed type and a method of making the same.
Gusseted, square-bottomed bags are disclosed in U.S. Pat. No.
2,496,796; 3,017,069 3,342,402; and 4,490,131. As disclosed in
these patents, the bags of this type generally comprise an outer
sheet of paper and an inner liner of an impervious heat sealable
material such as a plastic (synthetic resin). The bag is made of a
tube and the bottom end of the bag is formed by making a diamond
fold comprising a triangular fold portion and a partly rectangular
tab fold portion. After the triangular fold portion and the tab
fold portion are sealed, the bottom of the bag is completed by
folding over the tab fold portion onto a previously folded over
triangular fold portion. The tab fold portion is caused to adhere
to the bottom of the bag by applying suitable adhesive between the
contiguous faces of the tab fold portion and the triangular portion
of the bag bottom structure.
In accordance with the present invention there is provided a bag
and a method of makingm, the same which provides an improved bottom
construction which is very effectively sealed so that the bag can
contain many materials, including liquids, without any seepage
through the bag bottom. To this end, the bag is made by a method
wherein a special seal is applied at a location at the intersection
between the fin seal and the cross seal. This additional seal has
been found to improve the sealing of the bag bottom structure such
that the bag can be used in many applications which heretofore bags
of the indicated type were unacceptable. For example, in the
microwave cooking of food products, the bags are required to
contain liquids, such as water, oil, etc., during storage and
during the cooking processes wherein such liquids become very hot.
In these applications, even the slightest pin hole or other opening
in the seal of the bag bottom would cause a leakage or staining
problem. Bags made by the method of the invention comprising the
special seal at the intersection of the fin seal and cross seal
have overcome these problems.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-4 are plan views showing successive steps in the method of
making a bag in accordance with the invention.
FIG. 5 is a perspective view and FIG. 6 is a plan view showing the
special sealing step in the method in accordance with the
invention.
FIGS. 7 and 8 are plan views showing the final steps in the
formation of the bag bottom.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The bag and the method of making the same in accordance with the
invention is similar to that shown and described in U.S. Pat. No.
2,496,796, the essential difference being the manner in which the
sealing of the bag bottom is performed. As described in said
patent, the first step in the making of the bag is to form the
tube, indicated at 10 in FIG. 1, and having an outer sheet 11 of
paper and an inner liner 12 of an impervious, heat-sealable plastic
(synthetic resin) whereby the bag may be sealed in the manner
described in said patent. The tube forming step is performed on one
of the automatic bag making machines well known in the art wherein
the outer sheet 11 of the bag and the inner liner 12 are fed from
rolls into overlapping relation and then folded together and cut
into a tube 10 of the bellows-fold or gusseted type shown in FIG. 1
having front and back panels 14 and 16, respectively. During this
tube forming procedure, the inner liner 12 is sealed onto the inner
surface of the outer sheet 11 to provide an impervious bag
construction.
As described in said patent, a pair of spaced-apart, parallel slits
20 are formed at the bottom of the panel 16 of tube 10. The slits
20 extend longitudinally from the bottom edge of the panel 16 of
tube 10 and are spaced equidistantly from the longitudinal edges of
this panel 16. The slits 20 extend through both the outer sheet 11
and the liner 12 and thus provide a double play rectangular-shaped
tab portion 24.
The next step of the method is to form the bottom end of the tube
10 into a diamond fold as shown in FIG. 3 with the tab portion 24
located at one end and a triangular portion 30 at the other end,
and providing upwardly extending flaps 26 at the center of the
fold. The outer faces of flaps 26 are comprised of a portion of the
outer sheet 11 which has a two-ply thickness of sealable liner 12
therebetween. Flaps 26 are united by a vertical fold 28 which is at
the apex of the inner triangular portion 30 of the diamond fold. By
this construction, there will be no opening in this area when the
bottom of the bag is sealed as will be described hereafter.
While the bottom of the bag is being folded into the position shown
in FIG. 3, a heat seal is applied along strips at right angles to
flaps 26, as shown by the arrows in this figure. This is the first
sealing step in the sealing of the bag bottom. The center line of
this heat seal (known as the fin seal) is shown by dashed line 25
in FIG. 4. In this first sealing step, heat and pressure are
applied in an amount necessary to cause the opposing faces of the
portion of liner 12 within flaps 26 to adhere to each other and
thereby seal the entire length thereof. U.S. Pat. No. 2,846,928
discloses a method of applying the fin seal in detail. The flaps 26
are then folded to the position shown in FIG. 4 and lie flush with
the plane of the formed portion of the bag bottom.
With the bag in the condition shown in FIG. 4 of the Drawings, a
heat seal is applied along a strip extending across the protruding
tab portion 19 of the bag bottom. This is the second step in the
sealing of the bag bottom. The centerline of this heat seal (known
as the cross seal) is shown by dashed line 32 (FIG. 4), which
intersects with centerline 25 of the fin seal and is located
between the tab portion 24 and the fold or crease line 23 upon
which the final fold of this part of the bottom portion will be
made. In this second sealing step, heat and pressure are applied by
a spring-biased pressure roll across a strip centered on line
25.
The next step in the bag making procedure is the novel feature of
the invention, and is shown in detail in FIGS. 5 and 6. This step
is the third sealing step in the sealing of the bag bottom. As the
bag is moving along the conveyer 36 in the direction shown by the
arrow in FIG. 5 from the station whereat the cross seal is applied,
and while it is still relatively hot, it moves immediately into a
third sealing station 38 whereat there is provided a pressure roll
40 which is constructed and arranged to put added pressure on the
formed bag bottom as it moves along the conveyer 36, said pressure
being applied at an area which is generally rectangular and
centered on the intersection of the fin seal and the cross seal.
This novel sealing step provides a very strong seal 50 over a large
area and extends along both the fin seal and the cross seal and
around the entire area at the intersection thereof as is best shown
in FIGS. 5 and 6. To this end, roll 40 is mounted to rotate about
its shaft 41 and is provided at its periphery with a radially
extending projection or shoe portion 42 which applies pressure to
the formed bag bottom over a rectangular area 50 as shown in FIGS.
5 and 6.
The next step in the bag making procedure is to apply deposits of
glue or adhesive to the bottom portion of the tube 10 with the tube
10 in the flattened condition as shown in FIG. 6. The adhesive is
applied along strip-like areas 31 of tab portion 24 and at an area
33 of triangular portion 30 as shown in FIG. 6.
In the final steps of the method, the triangular portion 30 of the
diamond fold is bent over along the crease line 29, to the position
shown in FIG. 7, after which the bottom portion with the tab
portion 24 extending therefrom is folded over along crease line 23
onto the triangular portion 30 to complete the formation of the bag
bottom as shown in FIG. 8. During this latter step, the rectangular
tab portion 24 is pressed into contact on top of the triangular tab
portion 30 so that the adhesive areas 31 and 33 provide attachment
to contiguous areas of the bag bottom.
It will be apparent that a bag constructed as described above will
have the bottom portion effectively closed and sealed, not only to
prevent any sifting of finally powdered contents through the
bottom, but also, to seal the bag bottom so that it could even
contain liquids which are subjected to microwaving.
It is noted that the shoe portion 42 may be made with its bag
contacting or imprinting area having either a smooth or a knurled
surface.
* * * * *